Free-agent primer: Defensive backs

A dozen teams threw for more than 4,000 yards through the air last season. Just one, the Jets, failed to top the 3,000-yard mark. The NFL's trend toward pass-happy offenses keeps chugging along, and defenses are scrambling to adjust.

There has been a growing emphasis on adaptable defenders, not only up front in the DE/OLB role but also in the secondary: safeties who can slide down and play like linebackers; cornerbacks who can cover the slot, slide outside in man or drop deep in zone; three-down DBs comfortable as blitzers or against the run.

"I think it’s real important to have that versatility because oftentimes, your nickel defense might play as many as 500 or 550 snaps in a year out of your 1,000 or 1,100 snaps," new Falcons head coach Dan Quinn said. "When you have guys who can play on first and second down and then kick down to play another position on third down, that kind of versatility just adds all kind of value to your team."

Any defensive back who fits that description stands to get paid this off-season. Of course, so too do those cornerbacks who can lock down one side of the field or any safeties with potent sideline-to-sideline range.

The relative lack of impact defensive backs available will accelerate the race to the free agency finish line come next week. Our look ahead at the top cornerbacks and safeties on the market:

Overrated players

• Byron Maxwell, CB: Stick with me here. Maxwell is by most accounts the top available cornerback, maybe even by a significant margin. He's big and fast and physical. Here's the rub, though: Maxwell has been playing in the brilliant Seattle system, opposite Richard Sherman. He will be paid as a No. 1 cornerback, and he might be able to handle those duties, but it is a wait-and-see proposition. Considering the price tag Maxwell is going to carry, that's a little worrisome.

• Patrick Robinson, CB: This is a retroactive "overrated" designation. Robinson, a Round 1 pick in 2010, never came close to living up to his advance billing in New Orleans. A slight second-half bounceback last year may give him a little juice headed into free agency—he's still just 27 years old. Any long-term commitment would be a mistake at this point, though.

• Brandon Meriweather, S: Meriweather is sitting on 100 NFL games played (68 starts), so a front office valuing experience could bump him up the list. Aside from that element, off-and-on run support and the occasional head-hunting hit, there is not much of note in Meriweather's game these days.

• Antrell Rolle, S: The market absolutely favors Rolle, who started every game of his five-year Giants career. After Devin McCourty and Rahim Moore come off the board, Rolle could be next in line, with minimal safety depth behind him in free agency and almost none to speak of in the draft. On the flip side, he's coming off one of his worst years (Pro Football Focus graded him 81st out of 87 eligible safeties) and is 32 years old. Rolle is a safe option; he stands to be paid like a borderline elite safety.

Underrated players

• Alan Ball, CB: Ball's placement here assumes he can rediscover his 2013 form—he stood out that year on a 4-12 Jaguars team. His follow-up year was far less successful, as Ball struggled out of the gate before landing on injured reserve with a biceps injury. The lost '14 campaign will drive down Ball's price, which is good news for any team seeking some top-two cornerback help in free agency. Ball can hold his own against most receivers in the league.

• Rashean Mathis, CB: His career appeared headed to its conclusion before he latched on with Detroit in 2013. Now, Mathis has turned in back-to-back solid seasons. Even at 34 years of age (35 in August), he should earn a one- or two-year deal with little hesitation from the Lions or any other team.

• Tyvon Branch, S: As far as high-upside safety options go, Branch leads the charge, at least until teams get a crack at the new crop of rookies. Before injuries robbed him of most of the 2013 and '14 seasons, Branch was ascending into the upper echelon of NFL safeties, even as part of a struggling Raiders franchise. Can he find that mojo again? If so, someone might get a steal here.

• Da'Norris Searcy, S: Searcy took advantage of the opportunity created by Jairus Byrd's Buffalo exit, turning in 13 starts and a career-high three interceptions. No one will mistake Searcy for an All-Pro anytime soon, but he has elevated his value from "quality depth" to "reliable starter". The Bills appear ready to move forward with Duke Williams, so Searcy will have to find his next shot elsewhere.

Injured player to watch

• Louis Delmas, S: Who knows how good Delmas could be if he ever managed to stay healthy. It was close to a miracle that he made it through a full 16 games with Detroit in 2013, and he nearly repeated the feat with Miami last season ... only to tear his ACL in Week 14. Given his injury history, there is almost no way a team could hand him a guaranteed-money contract, especially as he rehabs his knee. But the talent is there if any GM wants to roll the dice.

Veteran to watch

[daily_cut.nfl]• Tramon Williams, CB: With all the hoopla surrounding Randall Cobb's contract situation, it's flown a bit under the radar that Green Bay could lose both Williams and Davon House, thereby leaving them without a clear-cut starter opposite Sam Shields. (Casey Hayward seems set in the slot role.) Williams turns 32 this month, which puts him right in the window where Packers GM Ted Thompson generally tends to let players walk. Overpaying for someone on the downside of his career has not been Thompson's M.O.

Green Bay's loss could be another franchise's gain. Williams has missed just one game in the past five seasons and he is certainly capable of holding down a No. 2 cornerback job.

Biggest wild card(s)

• Landon Collins, and then ...: If teams do start overpaying safeties once free agency begins, look no further than the 2015 draft class as an explanation. Alabama's Landon Collins has long been the lead dog among the safety prospects, but it may be another round or two after he comes off the board before another player at his position is selected.

• The Eagles: Every NFL team will add a body or two in the secondary this off-season, for depth purposes if nothing else. So what makes Philadelphia stand out here?

Well, to start, Chip Kelly. He's played it extremely close to the vest since taking over personnel control this off-season, paving the way for him to stun the league by shipping out LeSean McCoy for Kiko Alonso. His secondary, a trouble spot last season, still remains in ruins. Both Cary Williams and Bradley Fletcher are set to hit the market, as is safety Nate Allen.

Kelly continues to free up cap space, putting himself in position to take a run at Maxwell, McCourty, Rahim Moore and any other corner or safety he might fancy. Philadelphia also figures to be a wild card in the draft, with the Marcus Mariota-Kelly connection jumping off the page.

The Eagles are going to be major players in free agency, with the secondary likely to draw their central gaze.

• Will Troy Polamalu play?: The league-wide impact of this question is negligible (other than perhaps putting Pittsburgh in the running for safety help). And yet, few players have been as recognizable and, at times, impactful as Polamalu over the past decade-plus. An $8.25 million cap hit makes it nearly a foregone conclusion that Polamalu is done in the Steel City, either via release or retirement. If it's the former, could he latch on elsewhere—maybe following Dick LeBeau to Tennessee?